Methods and systems for improving operation of a video projector

ABSTRACT

A method of operating a video device includes determining an operating temperature, determining if the operating temperature is above normal operating temperature for the video projector, and setting the video projector in economy mode if the operating temperature is above the normal operating temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 60/703,433 filed on Jul. 29, 2005, the disclosure of which isincorporated in its entirety by reference herein.

FIELD

Aspects of the present invention generally relate to video displaymethods and systems.

BACKGROUND

Traditional video projection devices operate within a definedtemperature range. Traditional devices use a thermal switch to determinethe temperature of the device. Once the device moves outside of thisrange, the thermal switch cuts power to the device in order to preventthe device from overheating. However, a user is not given warning thatthe device is about to power down. Also, the thermal switch doesn't givethe video device flexibility in reducing power instead of powering down.Additionally, the thermal switch does not take into account otherenvironmental conditions such as air pressure.

SUMMARY

Aspects of the present invention concern a method for operating a videoprojector. The method includes determining an operating temperature,determining if the operating temperature is above normal operatingtemperature for the video projector, and setting the video projector ineconomy mode if the operating temperature is above the normal operatingtemperature.

Additionally, aspects of the present invention concern a video device.The video device includes a video projector, a controller coupled to thevideo projector, a light source coupled to the controller forilluminating the video projector to produce video, a temperature sensorcoupled to the controller, logic coupled to the controller, thetemperature sensor, and the light source for determining an operatingtemperature, logic coupled to the controller, the temperature sensor,and the light source for determining if the operating temperature isabove normal operating temperature for the video projector, and logiccoupled to the controller, the temperature sensor, and the light sourcefor setting the video projector in economy mode if the operatingtemperature is above the normal operating temperature.

Additional aspects of the present invention will be set forth in part inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The aspectsof the present invention will be realized and attained by means of theelements and combinations particularly pointed out in the appendedclaims.

Further, it is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the present invention, asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several aspects of the presentinvention and together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a diagram illustrating a system for displaying a videoconsistent with aspects of the present invention;

FIG. 2 is a rear view diagram illustrating a system for displaying avideo consistent with aspects of the present invention;

FIG. 3 a is a diagram illustrating a DLP video projector consistent withaspects of the present invention;

FIGS. 3 b-f are various views illustrating an integrated video projectorand video source consistent with aspects of the present invention;

FIG. 3 g is a diagram illustrating a DLP video projector consistent withaspects of the present invention;

FIGS. 4 a and 4 b are diagrams illustrating a display screen consistentwith aspects of the present invention; and

FIG. 5 is a flow chart illustrating a method of operating a videoprojector consistent with aspects of the present invention.

DETAILED DESCRIPTION

Aspects of the present invention relate to systems and methods whichimprove the operation of a video projection device. A video projectiondevice includes a temperature sensor for measuring the operatingtemperature of the device. If the temperature of the device movesoutside a normal operating range but not above a critical temperature,the device is placed in economy mode instead of being powered down.Thus, the device may continue to operate at higher temperatures.

Further, if the device is operating in economy mode because it is abovenormal temperature, the device display displays a notice image to theuser to remind the user that the device is operating in economy mode. Ifthe device moves above a critical temperature, the device displays anotice image to warn a user the device is powering down. Additionally,the device includes an air pressure sensor to measure air pressure.

Additionally, the temperature at which the display device returns tonormal mode from economy mode may be set different from the normaloperating range. By setting the temperature at which the display devicereturns to normal mode from economy mode different from the normaloperating range, the display device may be prevented from oscillatingbetween economy and normal modes if the operating temperature is varyingaround the limits of the normal operating range.

Reference will now be made in detail to various aspects of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIG. 1 illustrates a system 100 for displaying video consistent withaspects of the present invention. System 100 includes a display screen102 for viewing video projected from a video projector 104. System 100further includes a video source 106 which transmits a video signal tovideo projector 104. The video projected onto display screen 102 may bemoving video or still images. Video projector 104 may be any type ofvideo projector capable of receiving a video signal and converting thevideo signal to a viewable image to be displayed on display screen 102.For example, video projector 104 may be a digital light processing(“DLP”) video projector, a liquid crystal (“LCD”) video projector, orcathode-ray tube (“CRT”) projector.

As illustrated in FIG. 1, video source 106 supplies video projector 104with a video signal to be displayed on video screen 102. Video source106 may be any standard video equipment capable of generating a videosignal readable by video projector 104. For example, video source 106may be a Digital Versatile Disk (“DVD”) player, laser disk player,Compact Disk (“CD”) player, Video CD (“VCD”) player, VHSplayer/recorder, Digital Video Recorder (“DVR”), video camera, videostill camera, cable receiver box, or satellite receiver box. Videosource 106 may also be a standard laptop or desktop computer. Oneskilled in the art will realize that the preceding list of standardvideo equipment is exemplary and video source 106 may be any devicecapable of generating a video signal readable by video projector 104.Furthermore, video source 106 may be integrated with video projector104. Additionally, video projector 104 may be coupled to multiple videosources 106.

FIG. 2 is a back view of video projector 104 illustrating input/outputports 200 for sending and receiving signals consistent with aspects ofthe present invention. Video source 106 may be coupled to one of theinput/output ports 200. As illustrated in FIG. 2, input/output ports 200include a S-video input 202, DVI-I input 204, component video input 206,VGA input 208, audio input 210, coaxial video input 212, and coaxialaudio input 214.

Input/output ports 200 may include additional input and output ports.For example, input/output ports 200 may include ports any number of aS-video input, S-video output, composite video input, composite videooutput, component video input, component video output, DVI-I videoinput, DVI-I video output, coaxial video input, coaxial video output,audio input, audio output, infrared input, infrared output, RS-232input, RS-232 output, VGA input, or VGA output. One skilled in the artwill realize that the preceding list of input and output ports isexemplary and that input/output ports 200 may include any port capableof sending or receiving an electrical signal. Input/output ports 200 arecoupled to the internal components of video projector 104.

FIG. 3 a illustrates an exemplary DLP video projector 300 which may beused as video projector 104. DLP video projector 300 is an example ofone type of projector which may be used with system 100. One skilled inthe art will understand that any type of video projector may be usedwith system 100 such as a CRT projector or an LCD projector.

DLP video projector 300 may include a controller 318 and a bus 324.Controller 318 may include components to control and monitor DLP videoprojector 300. For example, controller 318 may include a processor,non-volatile memory, and mass storage. All the components of DLP videoprojector 300 may be coupled to bus 324 to allow all the components tocommunicate with controller 318 and one another. DLP video projector 300includes a fan 322 to cool DLP video projector 300. Fan 322 may becoupled to bus 324. DLP video projector 300 also includes a power supply(not shown) coupled to all the components.

DLP video projector 300 contains a light source 302 for generating lightto produce a video image. Light source 302 may be, for example, anultra-high performance (“UHP”) lamp capable of producing from 50-500watts of power. Light source 300 may be coupled to bus 324 tocommunicate with other components. For example, controller 318 or DLPcircuit board 310 may control the brightness of light source 302.

Light generated by light source 302 passes though optics 304, 308 andcolor filter 306. Optics 304 and 308 may be, for example, a condenserand a shaper, respectively, for manipulating the light generated bylight source 302. Color filter 306 may be, for example, a color wheelcapable of spinning at various speeds to produce various colors.

Video projector 300 also contains a DLP circuit board 310. DLP circuitboard 310 may include a digital micro-mirror device, a processor, andmemory. For example, DLP circuit board 310 may be a DARKCHIP2 orDARKCHIP3 DLP chip manufactured by TEXAS INSTRUMENTS. DLP circuit board310 is coupled to bus 324 to receive the video signal received frominput/output ports 320 and to communicate with controller 318. DLPcircuit board 310 reflects light from light source 302 using the digitalmicro-mirrors and generates video based on the video signal to bedisplayed on video screen 202. DLP circuit board 310 reflects light notused for the video onto light absorber 312. Light reflected by DLPcircuit board 310 used for the video passes through lens housing 314 andlens 316. Lens 316 focuses the video to be displayed on display screen102. Lens housing 314 may include a manual lens moving mechanism or amotor to automatically move lens 316. The manual lens moving mechanismor motor allows the position of lens 316 and, as a result, shift theposition of the video displayed on display screen 102. The shifting maybe achieved by moving lens 316 in any combination of the x, y, or zdirections.

DLP video projector 300 also includes input/output ports 320.Input/output ports 320 may be a single port or multiple ports.Input/output ports 320 enables DLP video projector to receive videosignals, receive signals from a remote control device, and outputsignals to other sources. For example, input/output ports 320 mayinclude ports as illustrated in FIG. 2 or any number of a S-video input,S-video output, composite video input, composite video output, componentvideo input, component video output, DVI-I video input, DVI-I videooutput, coaxial video input, coaxial video output, audio input, audiooutput, infrared input, infrared output, RS-232 input, RS-232 output,VGA input, or VGA output. One skilled in the art will realize that thepreceding list of input and output ports is exemplary and thatinput/output ports 320 may include any port capable of sending orreceiving an electrical signal. Input/output ports 320 are coupled tobus 324. Signals input into DLP video projector 300 may be transferredto the various components of DLP video projector 300 via bus 324.Likewise, signals output of DLP video projector 300 may be transferredto input/output ports 320 via bus 324.

As stated above, video source 106 may be integrated with video projector104. FIGS. 3 b-f are various views of a video projection system 350which includes a video source and video projector integrated into asingle housing 352 consistent with aspects of the present invention.Video projection system 350 may be utilized as system 104 in videosystem 100. FIG. 3 b is a top view of video projection system 350consistent with aspects of the present invention. As shown in FIG. 3 b,video projection system 350 includes video projector 354 and a videosource 358 in a single housing. For example, video projector 354 may bea DLP projector and video source 358 may be a DVD player. Videoprojection system 350 includes a lens housing 356 located in a frontportion of video projector 354. Lens housing 356 may include variouslens used in projecting video onto a display screen. Further, videosource 358 includes a tray 360 for housing media read by video source358. For example, if video source 358 is a DVD player, tray 360 mayhouse DVD discs.

Further, as illustrated in FIG. 3 b, video projection system 350includes projector controls 362 for operating video projector 354. Forexample, projector controls 362 may be a power switch, zoom controls,input/output select controls, and picture mode controls. Videoprojection system 350 also includes video source controls 364. Forexample, video source controls 364 may be tray open/close controls,play/stop controls, and video search controls for operating video source358. Video projection system 350 may also be controlled by a remotedevice (not shown). For example, a remote device may include redundantprojector controls 362 and video source controls 364. Video projectionsystem 350 also includes speakers 366 for presenting soundscorresponding to video generated by video projection system 350.

FIG. 3 c is a front view of video projection system 350. As shown inFIG. 3 c, lens housing 356 is located in the front portion of housing352 of video projection system 350. Further, video source 358 and tray360 may be housed in the top portion of housing 352 of projection system350. FIG. 3 d is another front view of video projection system 350. FIG.3 d illustrates video projection system 350 when tray 360 is open forinserting media to be played by video source 358.

FIG. 3 e is a rear view of video projection system 350. As illustratedin FIG. 3 e, input/output ports 368 are located in a rear portion ofhousing 352 of video projection system 350. For example, input/outputports 368 may include an S-video input 370, DVI-I input 372, componentvideo input 374, VGA input 376, composite video input 378, RS-232 port380, audio input 382, audio output 384, and optical audio output 386,and power input 388. Input/output ports 368 may include additional inputand output ports (not shown). For example, input/output ports 368 mayinclude ports any number of a S-video input, S-video output, compositevideo input, composite video output, component video input, componentvideo output, DVI-I video input, DVI-I video output, coaxial videoinput, coaxial video output, audio input, audio output, infrared input,infrared output, RS-232 input, RS-232 output, VGA input, or VGA output.One skilled in the art will realize that the preceding list of input andoutput ports is exemplary and that input/output ports 368 may includeany port capable of sending or receiving an electrical signal.

Further, as illustrated in FIG. 3 e, speakers 366 are located in thesides of the rear portion of housing 352 of video projection system 350.Of course, speakers 366 may also be located in other portions of housing352. In addition, video projection system 350 may be coupled to otherspeakers (not shown) that are external to housing 352.

FIG. 3 f is a block diagram illustrating internal components of videoprojection system 350 consistent with aspects of the present invention.As illustrated in FIG. 3 f, video projection system 350 includes a DLPvideo projector 354 and a DVD player 358 integrated into a singlehousing 352. DLP video projector 354 is an example of one type ofprojector which may be used with video projection system 350. Oneskilled in the art would understand that any type of video projector maybe used with video projection system 350 such as a CRT projector or anLCD projector. Further, DVD player 358 is an example of one type ofvideo source which may be used with video projection system 350. Oneskilled in the art will understand that any type of video source may beused with video projection system 350.

DLP video projector 354 may include a controller 318 and a bus 324.Controller 318 may include components to control and monitor DLP videoprojector 354. For example, controller 318 may include a processor,non-volatile memory, and mass storage. All the components of DLP videoprojector 354 may be coupled to bus 324 to allow all the components tocommunicate with controller 318 and one another. DLP video projector 354includes a fan 322 to cool DLP video projector 354. Fan 322 may becoupled to bus 324. DLP video projector 354 also includes a power supply(not shown) coupled to all the components.

DLP video projector 354 contains a light source 302 for generating lightto produce a video image. Light source 302 may be, for example, an UHPlamp capable of producing from 50-500 watts of power. Light source 300may be coupled to bus 324 to communicate with other component. Forexample, controller 318 or DLP circuit board 310 may control thebrightness of light source 302.

Light generated by light source 302 passes though optics 304, 308 andcolor filter 306. Optics 304 and 308 may be, for example, a condenserand a shaper, respectively, for manipulating the light generated bylight source 302. Color filter 306 may be, for example, a color wheelcapable of spinning at various speeds to produce various colors.

DLP projector 354 also contains a DLP circuit board 310. DLP circuitboard 310 may include a digital micro-mirror device, a processor, andmemory. For example, DLP circuit board 310 may be a DARKCHIP2 orDARKCHIP3 DLP chip manufactured by TEXAS INSTRUMENTS. DLP circuit board310 is coupled to bus 324 to receive the video signal received frominput/output ports 320 and to communicate with controller 318. DLPcircuit board 310 reflects light from light source 302 using the digitalmicro-mirrors and generates video based on the video signal to bedisplayed on display screen 102. DLP circuit board 310 reflects lightnot used for the video onto light absorber 312. Light reflected by DLPcircuit board 310 used for the video passes through lens housing 356 andlens 316. Lens 316 focuses the video to be displayed on display screen102. Lens housing 356 may include a manual lens moving mechanism or amotor to automatically move lens 316. The manual lens moving mechanismor motor allows the position of lens 316 and, as a result, shift theposition of the video displayed on display screen 102. The shifting maybe achieved by moving lens 316 in any combination of the x, y, or zdirections.

DLP video projector 354 also includes input/output ports 368.Input/output ports 368 may be a single port or multiple ports.Input/output ports 368 enables DLP video projector 354 to receive videosignals, receive signals from a remote control device, and outputsignals to other sources. For example, input/output ports 368 mayinclude ports as illustrated in FIG. 3 e or any number of a S-videoinput, S-video output, composite video input, composite video output,component video input, component video output, DVI-I video input, DVI-Ivideo output, coaxial video input, coaxial video output, audio input,audio output, infrared input, infrared output, RS-232 input, RS-232output, VGA input, or VGA output. One skilled in the art will realizethat the preceding list of input and output ports is exemplary and thatinput/output ports 368 may include any port capable of sending orreceiving an electrical signal. Input/output ports 368 are coupled tobus 324 and to audio bus 336. Signals input into DLP video projector 354may be transferred to the various components of DLP video projector 354via bus 324. Likewise, signals output of DLP video projector 354 may betransferred to input/output ports 368 via bus 324.

DLP video projector 354 also includes DVD player 358. DVD player 358 iscomposed DVD reader 326. DVD reader 326 may include a spindle motor forturning a DVD disc, a pickup head, and a head amplifier equipped with anequalizer. DVD reader 326 is coupled to a decoder/error correctioncircuit 328, a content scrambling system 330 for copy protecting DVDcontents, a program stream demultiplexer (“PS demultiplexer”) 332.

DVD player reads a DVD disc with DVD reader 326 by emitting laser lightfrom the pickup head in order to irradiate the DVD disc with apredetermined wavelength. The reflected light is converted to anelectric signal which is then output to the head amplifier. The headamplifier serves to perform signal amplification, waveform shaping anddigitization while decoder/error correction circuit 328 serves toperform 8-16 decoding and error correction. Next, content scramblingsystem 330 performs mutual authentication of the DVD disc and DVD player358 in order to confirm the authorization.

When the authorization is successfully finished, PS demultiplexer 332separates the program stream (“PS”) as read from the DVD disc into soundand video data in the form of packetized elementary streams (“PES”).Audio stream decoder 334 decodes the PES sound stream with soundcompression encoding technology in order to output audio signals. Forexample, audio stream decoder may utilize sound compression formats suchas MC, AC3, and MPEG. DLP circuit board 310 decodes and processes thevideo PES which would include video, sub-picture, and navigation data.For example, DLP circuit board 310 may utilize video compression formatssuch as MPEG 2. The decoded sound stream is transferred to DLP circuitboard 310 and DLP circuit board 310 synchronizes sounds, which istransferred to speakers 366 via sound bus 336 and video, which isgenerated by DLP video projector 354.

One skilled in the art will realize that controller 318 may be utilizedin combination with DLP circuit board 310 for producing video and soundfrom DVD player 358. Further, DLP circuit board 310 or controller 318may perform audio decoding functions similar to the functions asperformed by audio stream decoder 334.

FIG. 3 f is a block diagram illustrating internal components of DLPvideo projector 390 consistent with aspects of the present invention.DLP video projector 390 includes all the components of DLP videoprojector 300. In addition, video projection system 390 includes atemperature sensor 392. Temperature sensor 392 may be any type of sensorcapable of measuring the temperature inside of DLP video projector 390.For example, temperature sensor 392 may be a thermocouple. DLP videoprojector 390 also includes an air pressure sensor 394. Air pressuresensor 394 may be any type of sensor capable of measuring the airpressure inside DLP video projector 390. For example, air pressuresensor 394 may be a piezoelectric crystal sensor. Both temperaturesensor 392 and air pressure sensor 394 may be coupled to bus 324.Temperature sensor 392 and air pressure sensor 394 may be controlled bycontroller 318 or DLP circuit board 310. One skilled in the art willrealize that DLP video projector 350 may include a temperature sensor392 and air pressure sensor 394.

FIG. 4 a illustrates a detailed view of display screen 400 which may beused as display screen 102 consistent with aspects of the presentinvention. Display screen 400 is merely an example of one type ofdisplay screen which may be used with system 100. One skilled in the artwould understand that any type of display screen capable of displayingan image may be used with system 100. Display screen 400 includes aviewing screen 402 that retracts into a housing 404. Viewing screen 400may be constructed of materials that efficiently reflect the videoprojected from video projector 104. For example, viewing screen 404 maybe constructed of a white or gray vinyl fabric, glass beaded fabric,VIDEO SPECTRA fabric, High Contrast fabric, or High Power fabric. Oneskilled in the art would realize that the above materials are exemplaryand that viewing screen 402 may be constructed of any material orcombination of materials that reflects light. Optionally, a weight 406is attached to the bottom of viewing screen 402 to stabilize viewingscreen 402.

Display screen 400 also includes mounting brackets 408 which enabledisplay screen 400 to be attached to a wall or ceiling. FIG. 4illustrates mounting brackets 408 as located on the sides of housing404. Mounting brackets 408 may be located on any surface of housing 404to facilitate the mounting of display screen 400.

Viewing screen 402 may be manually or electrically retracted intohousing 404. If viewing screen 402 is manually retracted, housing 404contains an inertial locking mechanize and roller (not shown) attachedto viewing screen 402. The inertial locking mechanize enables a user toapply force to viewing screen 402 in order to retract or extend viewingscreen 402. As the viewing screen 402 retracts, viewing screen 402 iswound around the roller.

If viewing screen 402 is electrically retracted, housing 404 contains anelectrical motor and roller (not shown) attached to viewing screen 404.To electrically operate viewing screen 402, current is supplied to theelectrical motor to activate the motor and wind viewing screen 402around the roller in order to retract or extend viewing screen 402 intohousing 402. The current supplied to the electrical motor may becontrolled by a switch (not shown) located on housing 404. Additionally,a wireless receiver (not shown) may be attached to the electrical motorto enable the electrical motor to be controlled remotely. Additionally,a memory may be attached to the motor in order to store differentviewing screen positions to be recalled when needed.

FIG. 4 b is a diagram illustrating a display screen 450 which may beused as display screen 102 consistent with aspects of the presentinvention. Display screen 450 includes a viewing screen 402, a housing404, an optional weight 406, and optional mounting brackets 402 asdisplay screen 400. Display screen 450 functions in the same manner asdisplay screen 400 except that viewing screen 402 extends upward out ofhousing 404. Display screen 450 is merely an example of one type ofdisplay screen which may be used with system 100.

FIG. 5 illustrates a method 500 for operating video projector 104consistent with aspects of the present invention. Method 500 determinesthe operating temperature of video projector 104 and modifies theoperation of video projector 104 based on the reading. Method 500 may beperformed in a variety of situations. For example, video projector 104may initiate method 500 once video projector 104 is powered up. Then,video projector 104 may continually perform method 500 until videoprojector 104 is powered down. Further, video projector may performmethod 500 in response to a user command. One skilled in the art willrealize that the above situations for performing method 500 areexemplary and that method 500 may be performed in any situation in whichvideo projector 104 may be utilized.

Method 500 may be performed by any control and processing hardware,software, or combination thereof contained in video projector 104. Forexample, if DLP projector 300 is utilized, method 500 may be performedby controller 318, by DLP circuit board 310, by software stored incontroller 318, by software stored in DLP circuit board 310, or anycombination thereof. One skilled in the art will realize that method 500being performed by the components of DLP projector 300 is exemplary andthat method 500 may be performed by any hardware, software, orcombination thereof capable of performing processing and controlfunctions of the various components of video projector 104.

As illustrated in FIG. 5, video projector 104 first determines theoperating temperature of the video projector (stage 502). The operatingtemperature may be the temperature inside video projector 104, thetemperature of components of video projector 104, the temperatureoutside video projector 104, the ambient temperature of the environment,or combinations thereof.

Video projector 104 may determine the operating temperature when it isfirst power up. Likewise, the video projector 104 may determine theoperating temperature anytime after the video projector is powered up.

Once video projector 104 determines the operating temperature, videoprojector 104 determines if the operating temperature is above a normaloperating temperature range (stage 504). For example, the operatingtemperature range may be between approximately 0 degrees Celsius andapproximately 35 degrees Celsius. The temperature may be measured by atemperature sensor, for example as illustrated in FIG. 3 g. One skilledin the art will realize that the normal operating temperature range maybe any temperature capable of support by video projector 104 withoutdamaging video projector 104. The normal operating temperature range maybe set by the manufacturer of video projector 104. Also, a user of videoprojector 104 may set the normal operating temperature range.

If the operating temperature is riot above the operating temperaturerange, video projector 104 maintains normal operation (stage 505). Ifthe operating temperature is above the operating temperature range,video projector 104 determines if the operating temperature is above acritical temperature (stage 506). If video projector is above thecritical temperature, video projector 104 is in danger of overheating.As such, video projector 104 displays a notice image (stage 508). Thenotice image is projected as a normal video from video projector 104.Then, video projector 104 powers down to prevent any damage (stage 510).For example the critical temperature may be 45 degrees Celsius.

One skilled in the art will realize that the critical temperature may beany temperature capable of support by video projector 104 withoutdamaging video projector 104. The critical temperature may be set by themanufacturer of video projector 104. Also, a user of video projector 104may set the critical temperature.

Video projector stays powered down until the temperature returns to thenormal range (stage 512 and stage 505). Video projector 104 may alsodisplay the notice image if a user attempts to power up the videoprojector after video projector 104 has reached the criticaltemperature. Video projector 104 may display an image informing the userthat video projector 104 can return to normal mode.

If the operating temperature is above the operating temperature rangebut below the critical temperature, video projector 104 sets itself intoeconomy mode (stage 514). In economy mode, video projector may reducethe brightness of its light source by reducing the power to its lightsource. For example, the brightness may be reduced by 20% to 80% ofnormal brightness. For example, if DLP video projector 300 is utilized,controller 318 or DLP circuit board 310 may reduce the brightness oflight source 302.

While operating in economy mode, video projector 104 display a reminderimage to remind the user that video projector 104 is in economy mode(stage 516). Video projector 104 may display the reminder imageperiodically. Video projector may display the reminder image every 5minutes while operating in economy.

Once the operating temperature returns within the normal range, videoprojector 104 returns to normal operation (stage 502-505). Videoprojector 104 may display an image informing the user that videoprojector 104 has returned to normal mode. If the operating temperatureis not above the operating temperature range, video projector 104continues to operate normally and will continue to measure the operatingtemperature (stage 502).

Additionally, the temperature at which video projector 104 returns tonormal mode from economy mode may be set different from the normaloperating temperature range. For example, the temperature may be set toa lower value than the upper value of the normal operating temperaturerange. For example, if the upper value is 35 degrees Celsius, thetemperature at which video projector 104 returns to normal mode fromeconomy mode may be set to 33 degrees Celsius. By setting thetemperature at which video projector 104 returns to normal mode fromeconomy mode different from the normal operating temperature range,video projector 104 may be prevented from oscillating between economyand normal modes if the operating temperature is varying around thelimits of the normal operating temperature range.

Optionally, during the method 500, video projector may measure the airpressure and modify the normal operating temperature range and thecritical temperature. For example, if air pressure is higher, then theair is “thicker” and video projector 104 will be easier to cool.Accordingly, the normal operating temperature range and the criticaltemperature may be increased. If air pressure is lower, then the air is“thinner” and video projector will be harder to cool. Accordingly, thenormal operating temperature range and the critical temperature may bedecreased. The air pressure may be measured by an air pressure sensor,for example as illustrated in FIG. 3 g.

Other aspects of the present invention will be apparent to those skilledin the art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. A method for operating a video device, comprising: determining anoperating temperature; determining if the operating temperature is abovenormal operating temperature for the video projector; and setting thevideo projector in economy mode if the operating temperature is abovethe normal operating temperature.
 2. The method of claim 1, whereinsetting the video projector in economy mode comprises: reducing powersupplied to a light source of the video projector.
 3. The method ofclaim 2, wherein the power supplied to the light is reduced byapproximately 20%.
 4. The method of claim 1, wherein the normaloperating temperature is between approximately 0 degrees Celsius andapproximately 35 degrees Celsius.
 5. The method of claim 1, furthercomprising: continually measuring the operating temperature; andmaintaining the video projector in economy mode until the operatingtemperature is within normal operating temperature.
 6. The method ofclaim 5, further comprising: determining if the operating temperature isabove a critical temperature; powering down the video projector if theoperating temperature is above the critical temperature.
 7. The methodof claim 5 wherein the critical temperature is approximately 45 degreesCelsius.
 8. The method of claim 5, further comprising: displaying anotice image before powering down the video projector.
 9. The method ofclaim 8, further comprising: displaying the notice image in response toa command to power up after powering down.
 10. The method of claim 1,further comprising: determining an air pressure within the videoprojector; and modifying the normal operating temperature based on theair pressure.
 11. A video device comprising: a video projector; acontroller coupled to the video projector; a light source coupled to thecontroller for illuminating the video projector to produce video; atemperature sensor coupled to the controller; logic coupled to thecontroller, the temperature sensor, and the light source for determiningan operating temperature; logic coupled to the controller, thetemperature sensor, and the light source for determining if theoperating temperature is above normal operating temperature for thevideo projector; and logic coupled to the controller, the temperaturesensor, and the light source for setting the video projector in economymode if the operating temperature is above the normal operatingtemperature.
 12. The video device of claim 11, further comprising: logiccoupled to the controller, the temperature sensor, and the light sourcefor reducing power supplied to the light source of the video projector.13. The video device of claim 11, further comprising: an air pressuresensor coupled to the controller.
 14. The video device of claim 13,further comprising: logic coupled to the controller, the air pressuresensor, and the light source for determining an air pressure within thevideo projector; and logic coupled to the controller, the air pressuresensor, and the light source for modifying the normal operatingtemperature based on the air pressure.